From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 31E893E9F97; Thu, 19 Mar 2026 16:42:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773938535; cv=none; b=pJRvqyonlqRN+a6zXe7eHQHcnFsyzG1rr1egFDOzbxQJ1tjrX3IuRmyMvoWXAkA3PNE5y0aGLmJodYtvXxWBYBMg+pYLLsauSk0Efcdqv3cbNCVdAvlG5/2a5tkbgnDNnn5HxOUko9g/X3hSHnkddqz7JsrEZDOggxEotd6/YEE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773938535; c=relaxed/simple; bh=8zVTfTYoZU2NrEdEOC5GKqCbAOSUZ2wAmRkMKL+K5GA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F9d4KQzEwvLMZPhu3MRLmUfCIp5U/bV0QETulF0kLPehm4Gd05jdJuA/eedDKqWdY7myUROClpcyb/xg8gw1SgsN7ywXc9P5vVKy50AQlro+mUF0EphRXDDiaU754/F+ToxkcgTf8OAAbg9K7VXEhhKq3LvS6pHfn/Ye7xImNuk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5A7BA16F2; Thu, 19 Mar 2026 09:42:02 -0700 (PDT) Received: from [10.1.35.24] (e122027.cambridge.arm.com [10.1.35.24]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B4D393F7BD; Thu, 19 Mar 2026 09:42:02 -0700 (PDT) Message-ID: Date: Thu, 19 Mar 2026 16:42:00 +0000 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 07/48] arm64: RMI: Check for RMI support at KVM init To: Wei-Lin Chang , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve References: <20260318155413.793430-1-steven.price@arm.com> <20260318155413.793430-8-steven.price@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 19/03/2026 16:17, Wei-Lin Chang wrote: > On Wed, Mar 18, 2026 at 03:53:31PM +0000, Steven Price wrote: >> Query the RMI version number and check if it is a compatible version. A >> static key is also provided to signal that a supported RMM is available. >> >> Functions are provided to query if a VM or VCPU is a realm (or rec) >> which currently will always return false. >> >> Later patches make use of struct realm and the states as the ioctls >> interfaces are added to support realm and REC creation and destruction. >> >> Signed-off-by: Steven Price >> --- >> Changes since v12: >> * Drop check for 4k page size. >> Changes since v11: >> * Reword slightly the comments on the realm states. >> Changes since v10: >> * kvm_is_realm() no longer has a NULL check. >> * Rename from "rme" to "rmi" when referring to the RMM interface. >> * Check for RME (hardware) support before probing for RMI support. >> Changes since v8: >> * No need to guard kvm_init_rme() behind 'in_hyp_mode'. >> Changes since v6: >> * Improved message for an unsupported RMI ABI version. >> Changes since v5: >> * Reword "unsupported" message from "host supports" to "we want" to >> clarify that 'we' are the 'host'. >> Changes since v2: >> * Drop return value from kvm_init_rme(), it was always 0. >> * Rely on the RMM return value to identify whether the RSI ABI is >> compatible. >> --- >> arch/arm64/include/asm/kvm_emulate.h | 18 +++++++++ >> arch/arm64/include/asm/kvm_host.h | 4 ++ >> arch/arm64/include/asm/kvm_rmi.h | 56 +++++++++++++++++++++++++++ >> arch/arm64/include/asm/virt.h | 1 + >> arch/arm64/kernel/cpufeature.c | 1 + >> arch/arm64/kvm/Makefile | 2 +- >> arch/arm64/kvm/arm.c | 5 +++ >> arch/arm64/kvm/rmi.c | 57 ++++++++++++++++++++++++++++ >> 8 files changed, 143 insertions(+), 1 deletion(-) >> create mode 100644 arch/arm64/include/asm/kvm_rmi.h >> create mode 100644 arch/arm64/kvm/rmi.c >> >> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h >> index 5bf3d7e1d92c..f38b50151ce8 100644 >> --- a/arch/arm64/include/asm/kvm_emulate.h >> +++ b/arch/arm64/include/asm/kvm_emulate.h >> @@ -688,4 +688,22 @@ static inline void vcpu_set_hcrx(struct kvm_vcpu *vcpu) >> vcpu->arch.hcrx_el2 |= HCRX_EL2_EnASR; >> } >> } >> + >> +static inline bool kvm_is_realm(struct kvm *kvm) >> +{ >> + if (static_branch_unlikely(&kvm_rmi_is_available)) >> + return kvm->arch.is_realm; >> + return false; >> +} >> + >> +static inline enum realm_state kvm_realm_state(struct kvm *kvm) >> +{ >> + return READ_ONCE(kvm->arch.realm.state); >> +} >> + >> +static inline bool vcpu_is_rec(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + > > Hi, > > Both kvm_vm_is_protected() and vcpu_is_protected() are in kvm_host.h, do > you think that's a better place? Or is there a reason for this being in > kvm_emulate.h? I've no strong opinions, but as usual there are complications with the header include order. kvm_vm_is_protected/vcpu_is_protected are defined in asm/kvm_host.h, but struct kvm is defined in linux/kvm_host.h (which includes asm/kvm_host.h). The same is true for struct kvm_vcpu. This means that we can't have a static inline function using the kvm pointer (because the struct definition hasn't been reached). The 'solution' in the case of kvm_vm_is_protected/vcpu_is_protected is to use a macro - which works but has drawbacks (e.g. lack of type checking). I'll move them if there's a strong feeling they are in the wrong place, but to me it feels more like the macros in asm/kvm_host.h are just a hack to get around them being in the wrong place. Thanks, Steve > Thanks, > Wei-Lin Chang > >> #endif /* __ARM64_KVM_EMULATE_H__ */ >> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h >> index 5d5a3bbdb95e..9267a2f2d65b 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -27,6 +27,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> #define __KVM_HAVE_ARCH_INTC_INITIALIZED >> @@ -405,6 +406,9 @@ struct kvm_arch { >> * the associated pKVM instance in the hypervisor. >> */ >> struct kvm_protected_vm pkvm; >> + >> + bool is_realm; >> + struct realm realm; >> }; >> >> struct kvm_vcpu_fault_info { >> diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h >> new file mode 100644 >> index 000000000000..3506f50b05cd >> --- /dev/null >> +++ b/arch/arm64/include/asm/kvm_rmi.h >> @@ -0,0 +1,56 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * Copyright (C) 2023-2025 ARM Ltd. >> + */ >> + >> +#ifndef __ASM_KVM_RMI_H >> +#define __ASM_KVM_RMI_H >> + >> +/** >> + * enum realm_state - State of a Realm >> + */ >> +enum realm_state { >> + /** >> + * @REALM_STATE_NONE: >> + * Realm has not yet been created. rmi_realm_create() has not >> + * yet been called. >> + */ >> + REALM_STATE_NONE, >> + /** >> + * @REALM_STATE_NEW: >> + * Realm is under construction, rmi_realm_create() has been >> + * called, but it is not yet activated. Pages may be populated. >> + */ >> + REALM_STATE_NEW, >> + /** >> + * @REALM_STATE_ACTIVE: >> + * Realm has been created and is eligible for execution with >> + * rmi_rec_enter(). Pages may no longer be populated with >> + * rmi_data_create(). >> + */ >> + REALM_STATE_ACTIVE, >> + /** >> + * @REALM_STATE_DYING: >> + * Realm is in the process of being destroyed or has already been >> + * destroyed. >> + */ >> + REALM_STATE_DYING, >> + /** >> + * @REALM_STATE_DEAD: >> + * Realm has been destroyed. >> + */ >> + REALM_STATE_DEAD >> +}; >> + >> +/** >> + * struct realm - Additional per VM data for a Realm >> + * >> + * @state: The lifetime state machine for the realm >> + */ >> +struct realm { >> + enum realm_state state; >> +}; >> + >> +void kvm_init_rmi(void); >> + >> +#endif /* __ASM_KVM_RMI_H */ >> diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h >> index b51ab6840f9c..dc9b2899e0b2 100644 >> --- a/arch/arm64/include/asm/virt.h >> +++ b/arch/arm64/include/asm/virt.h >> @@ -87,6 +87,7 @@ void __hyp_reset_vectors(void); >> bool is_kvm_arm_initialised(void); >> >> DECLARE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); >> +DECLARE_STATIC_KEY_FALSE(kvm_rmi_is_available); >> >> static inline bool is_pkvm_initialized(void) >> { >> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c >> index c31f8e17732a..ddf7e57f23e8 100644 >> --- a/arch/arm64/kernel/cpufeature.c >> +++ b/arch/arm64/kernel/cpufeature.c >> @@ -289,6 +289,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar3[] = { >> static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = { >> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_CSV3_SHIFT, 4, 0), >> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_CSV2_SHIFT, 4, 0), >> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_RME_SHIFT, 4, 0), >> ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_DIT_SHIFT, 4, 0), >> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_AMU_SHIFT, 4, 0), >> ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_MPAM_SHIFT, 4, 0), >> diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile >> index 3ebc0570345c..e17c4077d8e7 100644 >> --- a/arch/arm64/kvm/Makefile >> +++ b/arch/arm64/kvm/Makefile >> @@ -16,7 +16,7 @@ CFLAGS_handle_exit.o += -Wno-override-init >> kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \ >> inject_fault.o va_layout.o handle_exit.o config.o \ >> guest.o debug.o reset.o sys_regs.o stacktrace.o \ >> - vgic-sys-reg-v3.o fpsimd.o pkvm.o \ >> + vgic-sys-reg-v3.o fpsimd.o pkvm.o rmi.o \ >> arch_timer.o trng.o vmid.o emulate-nested.o nested.o at.o \ >> vgic/vgic.o vgic/vgic-init.o \ >> vgic/vgic-irqfd.o vgic/vgic-v2.o \ >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index 29f0326f7e00..274d7866efdc 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -39,6 +39,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> >> @@ -104,6 +105,8 @@ long kvm_get_cap_for_kvm_ioctl(unsigned int ioctl, long *ext) >> return -EINVAL; >> } >> >> +DEFINE_STATIC_KEY_FALSE(kvm_rmi_is_available); >> + >> DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector); >> >> DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base); >> @@ -2921,6 +2924,8 @@ static __init int kvm_arm_init(void) >> >> in_hyp_mode = is_kernel_in_hyp_mode(); >> >> + kvm_init_rmi(); >> + >> if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE) || >> cpus_have_final_cap(ARM64_WORKAROUND_1508412)) >> kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \ >> diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c >> new file mode 100644 >> index 000000000000..fac151580c01 >> --- /dev/null >> +++ b/arch/arm64/kvm/rmi.c >> @@ -0,0 +1,57 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * Copyright (C) 2023-2025 ARM Ltd. >> + */ >> + >> +#include >> + >> +#include >> +#include >> + >> +static int rmi_check_version(void) >> +{ >> + struct arm_smccc_res res; >> + unsigned short version_major, version_minor; >> + unsigned long host_version = RMI_ABI_VERSION(RMI_ABI_MAJOR_VERSION, >> + RMI_ABI_MINOR_VERSION); >> + unsigned long aa64pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); >> + >> + /* If RME isn't supported, then RMI can't be */ >> + if (cpuid_feature_extract_unsigned_field(aa64pfr0, ID_AA64PFR0_EL1_RME_SHIFT) == 0) >> + return -ENXIO; >> + >> + arm_smccc_1_1_invoke(SMC_RMI_VERSION, host_version, &res); >> + >> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) >> + return -ENXIO; >> + >> + version_major = RMI_ABI_VERSION_GET_MAJOR(res.a1); >> + version_minor = RMI_ABI_VERSION_GET_MINOR(res.a1); >> + >> + if (res.a0 != RMI_SUCCESS) { >> + unsigned short high_version_major, high_version_minor; >> + >> + high_version_major = RMI_ABI_VERSION_GET_MAJOR(res.a2); >> + high_version_minor = RMI_ABI_VERSION_GET_MINOR(res.a2); >> + >> + kvm_err("Unsupported RMI ABI (v%d.%d - v%d.%d) we want v%d.%d\n", >> + version_major, version_minor, >> + high_version_major, high_version_minor, >> + RMI_ABI_MAJOR_VERSION, >> + RMI_ABI_MINOR_VERSION); >> + return -ENXIO; >> + } >> + >> + kvm_info("RMI ABI version %d.%d\n", version_major, version_minor); >> + >> + return 0; >> +} >> + >> +void kvm_init_rmi(void) >> +{ >> + /* Continue without realm support if we can't agree on a version */ >> + if (rmi_check_version()) >> + return; >> + >> + /* Future patch will enable static branch kvm_rmi_is_available */ >> +} >> -- >> 2.43.0 >>